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HUG - here for all audio enthusiasts

Since its inception ten years ago, the Harbeth User Group's ambition has been to create a lasting knowledge archive. Knowledge is based on facts and observations. Knowledge is timeless. Knowledge is human independent and replicatable. However, we live in new world where thanks to social media, 'facts' have become flexible and personal. HUG operates in that real world.

HUG has two approaches to contributor's Posts. If you have, like us, a scientific mind and are curious about how the ear works, how it can lead us to make the right - and wrong - decisions, and about the technical ins and outs of audio equipment, how it's designed and what choices the designer makes, then the factual area of HUG is for you. The objective methods of comparing audio equipment under controlled conditions has been thoroughly examined here on HUG and elsewhere and can be easily understood and tried with negligible technical knowledge.

Alternatively, if you just like chatting about audio and subjectivity rules for you, then the Subjective Soundings sub-forum is you. If upon examination we think that Posts are better suited to one sub-forum than than the other, they will be redirected during Moderation, which is applied throughout the site.

Questions and Posts about, for example, 'does amplifier A sounds better than amplifier B' or 'which speaker stands or cables are best' are suitable for the Subjective Soundings area.

The Moderators' decision is final in all matters regarding what appears here. That said, very few Posts are rejected. HUG Moderation individually spell and layout checks Posts for clarity but due to the workload, Posts in the Subjective Soundings area, from Oct. 2016 will not be. We regret that but we are unable to accept Posts that present what we consider to be free advertising for products that Harbeth does not make.

That's it! Enjoy!

{Updated Nov. 2016A}
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CD Player for Super HL5 - suggestions?

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  • #31
    Psychosis vs Denial Symptom. Let's construct a solid test

    Is there another way, where it is possible to " prove" that there is no difference between CD players? I have read many DBT showing that listeners couldn't tell any difference but while we blame audiophiles' ignorance and lack of inquiring mind to get behind the truth, what have we done to prove that no such difference ever exist?

    How many members here would open their doors to prove that there's is no difference between a $600 and a $3000 CDP? What we have here is two camps. For both camps their objective is music. Not ordinary music but as close as live music. Instead, of probing into their mental deficiency by putting labels such as audiophilia, why not we establish a robust Double Blind Test that for anyone who cares can use that as a reference.

    Our concern is about some people who are spending more money than they can afford in their pursuit of their hobby. Those who can afford them, please continue buying the super expensive products that is befitting your social status. That would be like lecturing a man who owns several marques that a Camry is as good as his BMW 5 series. Well .....not quite but almost there.

    I have said it many times that I couldn't tell any difference between the few players that I have done DBT. At the same time, what have I done to prove that I couldn't hear the difference. Does it matter to those who asserts that there exist difference in various CDP? They are also doing the same thing, i.e. just like me, they are stating their observation which seemed to be valid and supported by many. Their behaviour maybe called psychosis and they maybe calling us people with denial symptoms or those with wooden ears.

    I propose to do an experiment in the hope it will be a good reference. I have a $600 Sony DVD/SACD player upgraded with XOclock and some mod to the output section that will be pitting against a Marantz SA11s2 . The list price was $3000 when I bought it. So how do you think I should proceed from here. Should I record the sound from both players and let you guys decide them.? I have a SPL meter for level matching, small condenser mic and a very quiet room.

    Can we move on with some solid evidence?

    ST

    Comment


    • #32
      Prove CD peformance to whom? And a test process ....

      Originally posted by STHLS5 View Post
      Is there another way, where it is possible to " prove" that there is no difference between CD players?....
      Now whilst this is laudable as a scientific experiment, let's just stop and think for a moment. Who do we actually want to prove a point to? And what would the potential consequences be?

      First, we here are part of the industry and as loudspeakers are at the very end of the reproduction chain, we are highly dependent upon our colleagues right back to the microphones in the recording studio for the music we reproduce. You know as well as I do that the hard-bitten audiophile has his own reasons for believing what he does. We are not here to evangelise a round earth theory to flat earthers. CD, amplifier, cable, turntable manufactures have an equal right to exist as we do, and providing their unpaid audiophile missionaries can be kept on a tight leash and away from the sensible music-appreciating Harbeth users/owners, we wish them well.

      Second, in my thread here I have touched on how this industry - indeed any consumer goods industry - thinks and operates. In a modern post-industrial society 'marketing' is absolutely crucial to identify and deliver products which none of us actually need but many of us have the disposable income to aspire to. Technical fact is far less important in this era that presentational beliefs. I have no problem with that, until those beliefs start feeding back (here) as facts, which they manifestly are not. So, if someone wants to believe that product A is audibly superior to product B - great! Let them. In fact, we should perhaps encourage them to have that belief because if A is more expensive than B (and surely, it must be if it sounds better?) more money is flowing from his bank into the supplier's bank. And that has to be a good thing in a static economy. So do we want to be seen as an impediment to the economic cycle, even the survival of audio dealers? Absolutely not. We stand for one principal alone: that of consumer purchase decisions based on informed facts.

      To answer your question as to how one would construct such a test. I did this very thing myself twenty nine years ago when CD arrived.

      There are thirteen initial steps to prepare for the critical subjective listening test. Shouldn't take more than about 30 mins.- faster when you are familiar with the process.

      1. Burn two identical audio CDs with fixed stereo sinewave tones from, say, 40Hz to 18kHz (or better) at a nominal -10dB or so, pausing on each tone for ten or fifteen seconds or so, long enough for your audio range DVM* to stabilise. I suggest that you generate as a first calibration tone for about 30 seconds of 1kHz at the nominal -10dB level. We'll use this to normalise our measurement process.

      2. Connect the DVM to the left channel phono output on your CD player. Connect the right channel to your amp and TURN DOWN THE VOLUME BEFORE YOU PRESS PLAY TO JUST ABOVE A WHISPER. This will allow you to hear the tones as they progress.

      3. If the DVM has a dB, ac volt scale select that and perhaps the 2v or 4v range. Many CD players output about 2v rms (some much more) for a fully modulated 0dB disc.

      4. Hopefully your DVM has a 'normalise' or 'ref' button. Get ready to press it.

      5. With the volume turned down, press play on the CD player and the set-up 1kHz tone should be audible on the right speaker.

      6. Observe DVM. It will jump to some millivolt reading - e.g. -12dB or any number

      7. Press 'normalise' or 'ref' on the DVM. If the meter is a dB meter, it will now read (hopefully) 0.00dB.


      Now we have calibrated our set-up we're ready to start collecting measurements of the CD player's frequency response aka how loud it is at each of our spot frequencies.


      8. Move to the first tone, 40Hz or whatever you generated. Without disturbing the meter, write down the displayed number - let's say, -2.3dB

      9. Move to the second tone; write the level down .... perhaps -2.0dB

      10. You'll know that the calibration hasn't drifted when you reach the 1kHz tone and that should read 0.00dB.

      11. Continue right up to the highest frequency. Stop the player.

      12. Switch off the amplifier and only then swap-over the CD player's leads. The meter is then connected across the right channel and you are listening to the left speaker.

      13. Repeat the entire process, recalibrating the meter with the initial 1kHz tone.

      Think about the results.

      * A cheap, supermarket DVM is not designed for accurate measurement of audio tones. It is designed for 50/60Hz single tone mains supply frequency only. You will need to spend perhaps $50 to buy a suitable quality AC meter for wide band audio and more for a first class dB meter.
      Alan A. Shaw
      Designer, owner
      Harbeth Audio UK

      Comment


      • #33
        The 13 steps to calibration

        Thank you for the 13 steps guide. I must have been doing the test wrong all these years. I thought level matching means setting the volume of 1 kHz test tone fixed on different equipments under test. For some reasons, I have always been reluctant to buy speakers, amplifiers or CDP based on measurements under test tones. Even if a speaker measures exactly as a Harbeth under the test tones I doubt it will be identical sounding.

        ST

        {Moderator's comment: Hold on! The 13 steps are just the preparation! You have to check the frequency response across the audio band *before* you adjust level to anticipate frequency response differences in the listening test! Agree?}

        Comment


        • #34
          Moving to the next step requires me to prepare some paperwork by way of example. It's an investment for me because the level-dependency issue (which we've talked about many times here) clearly is not obvious to the normal audio enthusiast. Hopefully, once and for all we can nail this.

          Whether we are comparing loudspeakers, amplifiers, CD players, DACS, cables, microphones, pianos or any sound generating or recording equipment, if we do not account for differences in level (another way of saying perceived loudness) between these sources we will not be making a valid comparison of their inherent sonic qualities. We will most likely merely be making a comparison in our ear/brain of nothing more or less exciting than a difference in loudness, not latent quality. This is an extremely fundamental issue.

          The ear's perception of sound is extremely closely linked to its loudness.

          Please wait a few days for me to prepare this. Thanks.
          Alan A. Shaw
          Designer, owner
          Harbeth Audio UK

          Comment


          • #35
            The ear helped us to hear how close predators were (and hence escape in time!)

            Originally posted by A.S. View Post
            Whether we are comparing loudspeakers, amplifiers, CD players, DACS, cables, microphones, pianos or any sound generating or recording equipment, if we do not account for differences in level (another way of saying perceived loudness) between these sources we will not be making a valid comparison of their inherent sonic qualities. We will most likely merely be making a comparison in our ear/brain of nothing more or less exciting than a difference in loudness, not latent quality. This is an extremely fundamental issue.

            The ear's perception of sound is extremely closely linked to its loudness.
            That makes sense - as a survival mechanism it's better to know that a predator is nearer (louder) rather than to precisely define which predator it is!

            Comment


            • #36
              Need a Hz frequency meter?

              I am following you but my SANWA DVM got no frequency measurement. Will get onewith Hz reading. This is more complicated than I thought and it explain why many dread to even attempt these things.

              ST

              {Moderator's comment: No you do not need a frequency display. As Alan said, you only need to generate known frequencies in a logical stepped sequence. With one channel driving the speakers as a monitor of which tone you are outputting, you just count the tones. Maybe we should author the test cd as as .iso image that you can burn, announcing each tone.}

              Comment


              • #37
                Selection of True RMS meter

                Now if I thought you need a frequency meter built into your DVM I would have said so wouldn't I!!!!

                There is one potential and quite problematic issue in trying to combine frequency measurements (which are NOT necessary if you make the test CD in a logical way) and then try and take a voltage (dB) measurement on the same instrument. Depending on the instrument's design, it may not be able to alternate between frequency and volts without a (hidden) internal reset. And if you read my thirteen step guide to setting-up, the essence of my process was to first establish a reference (1kHz tone) and use that to normalise the dB (voltage) readings, so that all subsequent readings are relative to that. Switching from volts to frequency may/will cancel the Reference, making it very difficult to make quick, easy, reliable dB measurements.

                I can see now that it will be far simpler and less ambiguous, and ultimately need less ongoing input from me, if I spend some time (invest some time, actually) in showing you exactly what to do; then you can copy me. But that needs a few days prep. here so please be patient. I'll move the whole thing into a TechTalk item.

                In the meantime, about the selection of the cheapest, simplest Digital Volt Meter that will do the job. Let me see what the catalogue offers .... inexpensive, mid-price and ideal meters

                >

                P.S. Now I've done some desk research finding these three examples, I cannot expect you to invest much in a fancy meter of the type we use. So I need to re-think the approach. I think I'll buy a cheap meter and actually test it's usability.
                Attached Files
                Alan A. Shaw
                Designer, owner
                Harbeth Audio UK

                Comment


                • #38
                  The effect of Digital filter?

                  While waiting for the guide, I continued with AB comparison. After two days listening between the two players, I switched over to a less than $100 DVD player and I immediately sensed the sound is not as good as the other two players. I cannot describe but there is some difference. The bass or the timing of the bass and in the separation between the instruments are among the things I can sense the difference. I have Interchanged the loudness level between both players so that one is louder than the other but the preference wasn't influenced by the loudness.

                  Since I am able to hear the difference between these players and knew where the difference is apparent. I look for the same difference between the previously same sounding players, i.e. the $600 vs $3000. Now, I do sense some difference. Not obvious but subtle.

                  Meanwhile, the Marantz comes with 3 different digital filters that engages different pre and post echo and cutting the higher frequencies at different point. I do not really know what they do since the filter starts above the frequencies of my hearing range but you can hear a very subtle difference between these settings. Could the digital filter be the cause for difference in sound between difference player? As far as I know all three players' FR is ruler flat so theoretically they shouldn't be any difference.

                  I am just stating what I observed.

                  ST

                  Comment


                  • #39
                    Did you check the frequency response of the players to a test CD?

                    You suggest that you are aware of the loudness difference between the CD players playing the same CD, one outputs a higher voltage than the other, hence sound louder. How did you turn down the louder one's volume so that it played at exactly the same loudness as the quieter one?
                    Alan A. Shaw
                    Designer, owner
                    Harbeth Audio UK

                    Comment


                    • #40
                      Difference in loudness

                      Originally posted by A.S. View Post
                      Did you check the frequency response of the players to a test CD?

                      You suggest that you are aware of the loudness difference between the CD players playing the same CD, one outputs a higher voltage than the other, hence sound louder. How did you turn down the louder one's volume so that it played at exactly the same loudness as the quieter one?
                      One player's output is 2Vrms and another one is 2.3Vrms. I tested the loudness by playing 1 kHz test tone (Denon Test CD) and set the level to 75dB at listening position. But what I did was I actually played the one I preferred less louder to see if it influence my preference. For now, I am not going to be a judge of which one sounds better between those two players.

                      Comment


                      • #41
                        AB test and Inputs crosstalk

                        I just observed a very faint crosstalk between different inputs. Previously, what I do was to connect the CD Players to input 1 and 2. Playing two identical CD simultaneously, I would change input 1 and 2 by turning the selector to compare the sound.

                        But since the sound is leaking to other inputs I tried with my other preamp and did notice it too leaks the sound to other inputs. I checked with my friend and he says his preamp too leaks to other inputs. It is a very very faint leakage which may or may not influence the AB test. It is a factor that need to be addressed.

                        ST

                        Comment


                        • #42
                          Is 2.3v compared with 2.0v significant?

                          Originally posted by STHLS5 View Post
                          One player output is 2Vrms and another one is 2.3Vrms....
                          A simple calculation then.

                          What we are saying is that the louder CD player is a number of decibels (dBs) louder than the quieter one. How significant is 2.3v output compared with 2.0v? Audiology and psychoacoustics works in decibels not volts so we need to convert from volts to dBs.

                          We can calculate that decibel difference. First, dBs are simply a shorthand way of comparing A with B. Or C with D. Or X with K. dBs are a compariative measurement. Unlike kgs and seconds and amperes dBs do not exist as single entities: there must be a pair of things to make a comparison. dBs is nothing more than a nice neat way of expressing a ratio, one number divided by another number.

                          So, using the inbuilt Windows calculator set to (view) scientific mode, we enter the following ....

                          a) 2.3 divided by 2.0

                          b) The answer is 1.15

                          c) Then we press the Log button; the display says 0.060697.... (don't need to know why)

                          d) Then we press (*) times then type 20 then = (don't need to know why)

                          e) The result is that 2.3v relative to 2.0v is a gain of 1.21dB

                          Agree?

                          We know from audiology text books and/or personal experience that a loudness difference of about 1.0dB is just enough for the careful listener to detect a very small difference in loudness, which the human brain will interpret as a difference in sound quality (specifically, sound spectrum). In the same way we can say that, if a tweeter unit is about 1dB louder than another nominally identical unit off the same production line, it might just sound a shade brighter to the trained, careful listener.

                          So yes, I don't doubt that as a careful dedicated listener you will experience a sonic difference between these players simply due to a difference in their output voltage. Let me guess: the louder one is the more expensive one? If I was designing a CD player that the marketing dept. wanted to sound 'full bodied and involving' under uncalibrated listening tests as you have described, I would make it play significantly lounder than a competitor unit .... not 2.3v rms but perhaps 3v, 3.5dB louder than the 2v player. That would give an obvious difference (in perceived sonic character) to even the most casual, dissinterested cloth-eared listener.
                          Alan A. Shaw
                          Designer, owner
                          Harbeth Audio UK

                          Comment


                          • #43
                            Loudness and Cd players

                            Originally posted by A.S. View Post

                            So yes, I don't doubt that as a careful dedicated listener you will experience a difference between these player simply due to a difference in their output voltage. Let me guess: the louder one is the more expensive one?
                            In terms of loudness, I say it was almost impossible to tell which louder if I listen with two players connected and playing simultaneously. Yes, the expensive one was with much higher output. But I have seen players that is priced 20 thousand dollars to have only about 200mVrms.

                            Anyway, I intentionally increased the level of the other player to be atleast 2 or 3 dB but still found the difference. Maybe, my judgment is clouded due to the bad third player.

                            ST

                            {Moderator's time: Frankly, you are chasing your own tail. Unless you equalise loudness precisely any concusions you draw are (sorry to say) scientifically meaningless. Can you find two 10k ohm presets or volume controls in your kit of parts?}

                            Comment


                            • #44
                              Comparing CD

                              Originally posted by STHLS5 View Post
                              {Moderator's time: Frankly, you are chasing your own tail. Unless you equalise loudness precisely any concusions you draw are (sorry to say) scientifically meaningless. Can you find two 10k ohm presets or volume controls in your kit of parts?}
                              I do not have them. Before that, in lieu of an instantaneous change over-box to do comparison between two players, will the use of preamp selectors be accepted as a valid test. The crosstalk, i.e. sound bleeding to the adjacent input, may give the average sound of two players at any one time and therefore it may not be a valid comparison.

                              100s over posts on various CD Players but in this thread no one else contributing. Sad.

                              ST

                              Comment


                              • #45
                                How can you be sure that the two amplifier inputs that you are using to switch between player A and B have the same sensitivity? Unless this is checked (by measurement) it is another unquantified variable.

                                As per my Rule 12 of Marketing here you have observed that very point: there isn't the intellectual curiosity about eliminating variables (such as loudness variation) before making valid comparisons between audio equipment. It doesn't matter how curious you, I or certain journalists are about the science behind audio, the public is disinterested in objectivity. And as long as that condition continues (which will be forever) the marketing of feelings will subordinate scientific facts. Just as well! Our modern economy depends upon selling and consuming expensive hair and skin conditioning products providing significant employment. Keep the cash register bell tinkling!

                                If you have the laudable aspiration of education on the matter of CD player performance, forget it. The inertia you are trying to overcome is immense. But internally, we are considering if/how we should allow contributions here which promote brands of amplifiers, cables, DACs and the all the rest based on nothing other than emotions. Are we here a shop window for products that we do not make, would never buy, know nothing about factually ourselves and obviously cannot endorse from a position of personal experience? We think we have a responsibility to our customers to provide total satisfaction with their audio system.

                                What we really want you to do is visit your hi-fi dealer. He (or she) is in business to provide long term customer satisfaction. They want you to make the right purchases using your own ears and then to tell your friends. They are significantly imperveous to marketing BS because they've seen it all and heard it all before. As an example, our member here, hifi_dave, knows more about audio equipment (and peoples needs) than I'll learn in five lifetimes. That's where you should head for knowledge.
                                Alan A. Shaw
                                Designer, owner
                                Harbeth Audio UK

                                Comment

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